Define pH ? Calculate the pH of
a) 10^–3 M HCl b) 10^–3 M H₂SO₄
c) 0.001 M NaOH d) 0.0008M Ba(OH)₂

Negative value of logarithm to the base 10 of hydrogen ion concentration is known as pH.
a) 10^–3 M HCl
pH = –log[H⁺] ; [H⁺] = 10^–3
pH = –log(10^–3) = –(–3log10) = 3
b) 10^–3 M H₂SO₄
pH = –log[H⁺]
[H⁺] = Molarity × basicity
[H⁺] = 10^–3 × 2
pH = –log(2 × 10^–3)
= 3 log10 – log2
= 3 – log2
= 3 – 0.3010 = 2.6990
c) 0.001 M NaOH
[OH^–] = Molarity × Acidity
= 0.001 × 1
= 0.001 = 10^–3
pOH = –log[OH]^– = –log 10^–3
= 3log10 = 3
pH + pOH = 14
pH = 14 – pOH
= 14 – 3 = 11
d) 0.0008 M Ba(OH)₂
[OH^–] = Molarity × Acidity
= 0.0008 × 2 = 16 × 10^–4
pOH = –log[OH]^–
= –log(16 × 10^–4)
= –log16 – log10^–4
= –1.2041 + 4log10
= 4 – 1.2041 = 2.7959
pH + pOH = 14
pH = 14 – pOH
= 14 – 2.7959 = 11.2041